The investigator's propose to continue development of a dual-camera image intensifier-based CT system as a radiation therapy simulator, as further described by their abstract. "Computed tomography (CT) has become increasingly important in radiotherapy planning: CT add-ons have been introduced for therapy simulators and specialized CT scanners have been developed as stand-alone therapy planning system. However, CT add-ons have poor throughput, which prevents sufficient image slices for adequate therapy planning, and often poor image contrast. CT-based simulators do not duplicate the physical environment of therapy machines and require extra floor space. Phase I research demonstrated that the innovative scheme of dual cameras with different gains optically coupled to the x-ray image intensifier of a simulator solves the dynamic range problem to provide the contrast necessary for CT and enables cone-beam CT solving the throughput problem. For Phase II, an in-house simulator will be modified to include the dual camera optics. A computer system capable of the human data rates and the intense computational task of volume image reconstruction will be built and programmed, based on an already existing prototype. Phase II testing will include anthropomorphic phantoms on the in-house simulator, culminating in limited clinical trials at the Veterans Administration Hospital, Milwaukee."